The present invention relates to an improvement within applicant's compression molded fiberglass grating apparatus as set forth in applicant's prior U.S. Pat. No. 3,772,126, issued Nov. 13, 1973. The apparatus of applicant's prior patent requires initially a rectangular metal block weaving form to be positioned on an underlying support with a top face bearing first and second sets of spaced parallel open ended slots, with respective sets of slots intersecting at right angles and weaving means for repetitive placement of continuous strands of resin wetted fiberglass alternately within respective slots of each set in a zig-zag manner. Projectable and retractable detents provided on the form at the open ends of the slots are engageable by the fiberglass strands to facilitate zig-zag depositing of the strands in the slots with the detents projected to hold the strands during the zig-zag layup and retracted to allow lay of the preceding layer of strands with spaced parallel slots.
In a true sense of the word, the strands are not woven, but are alternately layed in the slot, first in one direction and then in the opposite direction, with the detents acting at respective ends of the slots of the two sets, to hold strands at their overlapping reversing point at the end of the slots as they are filled into the slot, by the weaving machine running bar reversing direction, after the strands engage respective detents.
The manner of operation of the apparatus of the '126 Patent involves swinging a pair of substantially L-shaped weaving arms over the form in directions running respectively parallel to the slots of the two sets such as from front to back of the rectangular block form for one set of slots and from one lateral side to the other for the second set of slots. In swinging of the arm through a 180.degree. arc, to effect placement of the wetted strand within given parallel slots with the strands passing through spaced parallel apertures within the arms, the strands are required to follow a full 180.degree. arcuate path to a maximum vertical height at the center of the arc, significantly above the top of the form bearing the rectangular slots.
The applicant has found that such action inherently varies the tension of the strands as they are deposited within the slots due to the excessive travel of the strands about the arcuate path of the swinging arms. Additionally, while the wetted strands frictionally engage movable and static components of the apparatus such as the apertures within the swinging arm and apertures within the resin tank where they are initially directed for wetting by the catalyzed resins prior to deposit within the sets of slots, the tension set up during wetting has been inadequate to insure uniform layup and achievement of desired density of the fiberglass reinforcing strands within the molded resin grating.
It is therefore a primary object of the present invention to provide an improved weaving machine for the making of a fiberglass reinforced compression molded grating, wherein the catalyzed resin wetted fiberglass strands are more quickly inserted within the sets of spaced parallel slots of the weaving form, wherein the wetted fiberglass strands are subjected to continuous, uniform tension throughout the wetted strand insertion step, wherein tension on the strands may be readily varied depending upon the nature of the catalyzed resins being applied to the fiberglass strands and wherein the depositing of the catalyzed resin wetted strands in zig-zag fashion within the slotted form reduces the time span between wetting of the strands, weaving thereof into the grating form, transfer of the strands from the form to the preheated female mold, and the compression and curing of the resin within preheated male and female mold halves at a downstream press station.
With the foregoing objects and features in view, and such other objects and features which may become apparent from the specification, the invention will be understood from the following description taken in conjunction with the accompanying drawings in which like numerals designate like parts.